Semiconductor processing apparatuses

ABSTRACT

An apparatus for semiconductor processing includes: a) at least one support member comprising an upper surface for supporting a semiconductor wafer; b) a component through which the support member extends, the component comprising a front surface and a back surface, at least one of the support member and the component being movable relative to the other of the support member and the component such that the support member can support a wafer in an elevated position above the front surface and can be withdrawn into the component to lower the wafer relative to the front surface of the component; and c) a block joined to the support member below the component back surface, the block engaging the component back surface when the support member upper surface extends above the component to a predetermined distance, the block preventing the support member upper surface from extending beyond the front surface by more than the predetermined distance.

RELATED PATENT DATA

This patent resulted from a divisional application of U.S. patentapplication Ser. No. 09/136,883, which was filed on Aug. 19, 1998.

TECHNICAL FIELD

The invention pertains to methods and apparatuses of treatingsemiconductor wafers, and can have particular applicability to methodsof forming antireflective coating materials.

BACKGROUND OF THE INVENTION

Various semiconductor processing procedures involve elevating a waferabove a component to a first predetermined distance for a firsttreatment, and subsequently lowering the semiconductive wafer relativeto a surface of the component for a second treatment. For instance, oneprocess of forming an organic antireflective coating (ARC) involvesplacing a semiconductive wafer to a first predetermined distance over ahot plate for a first temperature treatment of the wafer, andsubsequently lowering the semiconductive wafer directly onto the hotplate for a second temperature treatment. More specifically, asemiconductive wafer coated with a liquid layer of the ARC material isplaced over a hot plate to the first predetermined distance. The liquidARC material is then subjected to a so-called “low temperature bake”.The low temperature bake is typically conducted at from about 80° C. toabout 110° C., for a time of from about 30 seconds to about 300 seconds,and at about atmospheric pressure. After the low-temperature bake, thewafer is lowered onto the surface of a hot plate and subjected to a“high temperature bake”. The high temperature bake is typicallyconducted at from about 120° C. to about 170° C., for a time of fromabout 30 seconds to about 120 seconds, and at about atmosphericpressure.

A purpose of the low-temperature processing is to remove solvents priorto the subsequent high-temperature processing. If such solvents were notremoved, rapid volatilization could occur in the high-temperatureprocessing to cause splattering of ARC material from the semiconductivewafer. A purpose of the high-temperature processing is to densify thedeposited ARC material, as well as to drive off any remaining solventsthat weren't completely removed by the low-temperature processing.

The above-described low-temperature and high-temperature processings canbe conducted with either a single hot plate, or with a pair of hotplates. If a pair of hot plates are utilized, one of the hot plates isdedicated to low-temperature processing, and the other is dedicated tohigh-temperature processing. The hot plates can have different surfacetemperatures. Alternatively, both hot plates can have approximatelyidentical surface temperatures, with the difference in processingtemperature being achieved by having the wafer elevationally displacedfrom the first hot plate during the low-temperature processing, and inphysical contact with the heated surface of the second hot plate duringthe high-temperature processing. The elevational displacement of thelow-temperature processing can be achieved with a “fixed holdoff” (i.e,with a structure configured to elevate the wafer above the first hotplate by a fixed distance, such structure can comprise, for example,spherical balls held in a groove in the hot plate, or pins extendingbetween the hot plate and the wafer).

If a single hot plate is utilized for both the low and high temperatureprocessings, the semiconductive wafer is generally supported by rodsextending through the hot plate and movable relative to the hot plate.The rods are elevated to hold the semiconductive wafer above the hotplate during the low-temperature processing, and then lowered to lay thesemiconductive wafer directly upon the hot plate surface during thehigh-temperature processing.

The single hot plate methods can be advantageous over dual hot platemethods, in that the processing is simpler. Specifically, the dual hotplate methods require a semiconductive wafer transfer step between afirst hot plate utilized for low-temperature processing and a second hotplate utilized for high-temperature processing, and such transfer stepis eliminated in single hot plate processes. However, single hot plateprocesses presently suffer a disadvantage in that it is difficult toaccurately and reproducibly control the elevational height of asemiconductive wafer during low-temperature processing steps.Specifically, it is found that the support rods extending through asemiconductive wafer do not always hold a semiconductive wafer at thesame height above a hot plate heated surface during repeatedlow-temperature processing. Subtle variations in height can createvariations in the temperature at which a semiconductive wafer isprocessed, which can adversely cause variability amongst treatedsemiconductive wafers when multiple semiconductive wafers are processedsequentially. Accordingly, it would be desirable to develop alternativesemiconductive processing methods wherein the elevational height of aprocessed wafer can be more tightly controlled.

SUMMARY OF THE INVENTION

In one aspect, the invention encompasses a semiconductor processingapparatus. The apparatus comprises at least one support member having anupper surface for supporting a semiconductor wafer. The apparatus alsocomprises a component through which the support member extends. Thecomponent has a front surface and a back surface, and at least one ofthe support member and the component is movable relative to the other ofthe support member and the component. The apparatus includes amechanical stop associated with one of the support member and thecomponent and not associated with another of the support member and thecomponent. The mechanical stop engages the other of the support memberand the component to which it is not associated when the support memberupper surface extends above the component to a predetermined distance.

In another aspect, the invention encompasses a semiconductor processingmethod. At least one support member is provided. The support member hasan upper surface for supporting a semiconductor wafer. A component isprovided. The support member extends through the component. Thecomponent comprises a front surface and a back surface. At least one ofthe support member and the component is movable relative to the other ofthe support member and the component such that the support member cansupport a wafer in an elevated position above the front surface and canbe withdrawn into the component to lower the wafer relative to the frontsurface of the component. A block is provided to be joined to thesupport member below the component back surface. The block engages thecomponent back surface when the support member upper surface extendsabove the component to a predetermined distance. The block prevents thesupport member upper surface from extending beyond the front surface bymore than the predetermined distance. The at least one of the supportmember and the component is moved to elevate the support member relativeto the component until the block is engaged against the component backsurface. A semiconductor wafer is provided on the elevated supportmember upper surface. The component is utilized to treat thesemiconductor wafer while the semiconductor wafer is on the elevatedsupport member and elevated above the component to the predetermineddistance. The at least one of the support member and the component ismoved to lower the semiconductive wafer relative to the component. Afterthe semiconductor wafer is lowered, the component is utilized to treatthe semiconductor wafer.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

FIG. 1 is a diagrammatic, schematic, cross-sectional view of asemiconductor wafer processing apparatus of the present invention.

FIG. 2 is a view of the FIG. 1 apparatus shown at a first operationalstep.

FIG. 3 is a view of the FIG. 1 apparatus shown at a second operationalstep.

FIG. 4 is a diagrammatic, schematic, cross-sectional view of analternative construction of a semiconductor wafer processing apparatusof the present invention.

FIG. 5 is a schematic, top-view of a semiconductor wafer processingapparatus of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of theconstitutional purposes of the U.S. Patent Laws “to promote the progressof science and useful arts” (Article 1, Section 8).

An apparatus 10 of the present invention is illustrated incross-sectional view in FIG. 1. Apparatus 10 comprises a component 12having a front surface 16 and a back surface 18. Front surface 16 ispreferably configured to treat a semiconductive wafer that is supportedon or above front surface 16. For instance, component 12 can comprise aheater, such as, for example, a hot plate, and front surface 16 can be aheated surface of such heater. Component 12 contains a plurality oforifices 22 extending from back surface 18 to front surface 16.

Apparatus 10 further comprises a plurality of support members 14 havinguppermost surfaces 15. Upper surfaces 15 of the individual components 14are preferably all at a common elevational height relative to uppersurface 16 of component 12. Support members 14 extend within orifices 22and through component 12. Support members 14 are joined to a common base20, which is in turn coupled with a power or driving source 60configured to move base 20 up and down relative to component 12. Such upand down movement of base 20 slides support members 14 within orifices22 to vary an elevational displacement of upper surfaces 15 relative tocomponent 12. An example preferred power or driving source would be apneumatically powered source.

A mechanical stop (block) 30 is joined to base 20, and accordingly isjoined to support members 14 through base 20. Block 30 is above base 20and under component 12, and extends upwardly from base 20 in a directionof component 12. In the shown embodiment, block 30 comprises a screw 32threadedly engaged with a nut 34. Screw 32 has a head 36 and a threadedextension 38 which extends through nut 34 and into base 20. Inoperation, screw head 36 engages back surface 18 of component 12 whensupport member upper surfaces 15 extend above component upper surface 16to a predetermined distance. Screw head 36 comprises a substantiallyplanar top surface which is stop plane that engages back surface 18.Back surface 18 also comprises a substantially planar surface thatfunctions as a second stop plane. The predetermined distance can be setby adjusting a height of screw head 36 relative to base 20. Nut 34 locksscrew 32 in a desired position to fix the distance between screw head 36and base 20. Upward motion of base 20 is stopped when screw head 36 ofblock 30 engages back surface 18 of component 12. Accordingly, block 30can prevent support member upper surfaces 15 from extending beyond frontsurface 16 of component 12 by more than the predetermined distance. Itis noted that the orientation of screw 32 of block 30 can be inverted,as shown in FIG. 4. In such inverted orientation, screw 32 comprises ascrew end 37 which engages back surface 18 of component 12 to stopupward movement of support members 14.

In the shown embodiments, block 30 is removably joined to base 20, andadjustable so that a predetermined distance can be varied. It is to beunderstood, however, that the invention encompasses other embodiments(not shown) wherein block 30 is permanently affixed to base 20 by, forexample, welding or gluing, such that block 30 is not removable frombase 20, and such that a predetermined distance is fixed. Also, it isnoted that in the shown embodiment block 30 is configured to physicallycontact back surface 18 of component 12 as block 30 engages back surface18. However, the invention encompasses other embodiments (not shown)wherein block 30 engages back surface 18 through one or moreintermediate structures provided between back surface 18 and block 30.

Operation of apparatus 10 is described with reference to FIGS. 2 and 3.Referring to FIG. 2, a semiconductor wafer 40 is provided to besupported by upper surfaces 15 of support members 14. Semiconductorwafer 40 can comprise, for example, a wafer of monocrystalline silicon,and can be provided on upper surfaces 15 by conventional methods. Base20 is pushed upwardly by power source 60, either before or afterprovision of semiconductor wafer 40, until block 30 engages back surface18 of component 12. Semiconductor wafer 40 is thus provided at apre-determined distance above front surface 16 of component 12.

Semiconductor wafer fragment 40 is subjected to first processingconditions while it is elevated above front surface 16 by thepredetermined distance. For instance, in one embodiment of the inventioncomponent 12 comprises a heater (such as, for example, a hot plate) anda liquid ARC material (not shown) as provided over an upper surface ofsemiconductor wafer 40. Front surface 16 of component 12 is a heatedsurface, and the pre-determined distance by which wafer 40 is elevatedover front surface 16 is chosen such that the ARC material is heated toa first temperature of from about 80° C. to about 110° C. The heatingpreferably continues for a time of from about 30 seconds to about 300seconds to accomplish a low-temperature processing.

After wafer fragment 40 is subjected to the first processing conditions,base 20 is lowered as shown in FIG. 3. Such lowering encompasseslowering support members 14 into component 12. In the shown embodiment,the lowering leaves semiconductor wafer 40 supported on front surface 16of component 12. In the above-described embodiment in which component 12is a heater and is utilized for treating an ARC material, the loweringof support members 14 places the ARC material in closer proximity toheated front surface 16 of component 12. The closer proximity causes theARC material to heat to a second temperature that is higher than thefirst temperature to which it was heated in the step of FIG. 2.Preferably, such second temperature is from about 120° C. to about 170°,and is maintained for from about 30 seconds to about 120 seconds. Afterthe heating to the second temperature, wafer 40 can be removed from overcomponent 12 by conventional methods.

It is noted that in the above-described embodiments, support members 14are moved relative to component 12. It is to be understood, however,that the invention encompasses other embodiments (not shown) whereincomponent 12 is moved relative to support members 14. Additionally, itis noted that in the shown embodiment mechanical stop 30 is associatedwith support members 14 (through base 20) and engages component 12.However, the invention encompasses other embodiments (not shown) whereinmechanical stop 30 is associated with component 12 and engages supportmembers 14 (such as, for example, through base 20).

A preferred embodiment orientation of support members 14 and block 30 isdescribed with reference to FIG. 5. Specifically, FIG. 5 illustrates atop view of a preferred apparatus 10 b of the present invention. Indescribing apparatus 10 b, similar numbering to that utilized indescribing the apparatus of FIGS. 1-3 will be used, with differencesindicated by the suffix “b” or by different numerals. Apparatus 10 bcomprises three support members 14 extending through a component 12.Apparatus 10 b further comprises a block 30 (shown in phantom view)centrally located relative to the three support members 14. Block 30 andsupport members 14 are joined to a base (not shown) analogous to base20. The central location of block 30 can provide more balanced forcesrelative to support members 14 when block 30 is engaged againstcomponent 12 than would otherwise occur if block 30 were not centrallylocated.

In the shown embodiments, the apparatuses comprise three support members14. It is to be understood, however, that the invention encompassesother embodiments (not shown) wherein less than three support membersare utilized, and encompasses yet other embodiments (not shown) whereinmore than three support members are utilized.

Also, it is noted that the embodiments of the invention described aboveare described with specific application to a process for heating asemiconductor wafer to treat an antireflective coating material.However, it is to be understood that the invention can have applicationto any semiconductor wafer fabrication process wherein a wafer is to beelevated above a component to an initial first distance, andsubsequently is to be provided to a lower elevation relative to asurface of the component.

In the above-described embodiments, the semiconductor wafer is supportedon a surface of the component when the support members (14) areretracted into component 12. However, it is to be understood that theinvention encompasses other embodiments (not shown) wherein additionalsupport members are provided between an upper surface of component 12and wafer 40, and wherein wafer 40 is supported on such other componentsas support members 14 are withdrawn.

FIGS. 1-5 illustrate the relative orientations of component 12 andsupport structures 14, and do not show supporting hardware attached tocomponent 12 and support structures 14. However, it is to be understoodthat component 12 and support structures 14 will generally have hardwareassociated therewith to support them and hold them in the shown relativeorientations. The fabrication of such supporting hardware is well withinthe skill of persons of ordinary skill in the art.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

What is claimed is:
 1. A semiconductor processing apparatus comprising:a support member comprising an upper surface for supporting asemiconductor wafer; the support member being joined to a base; acomponent through which the support member extends, the componentcomprising a front surface and a back surface, the support member beingmovable relative to the component such that the support member cansupport a wafer in an elevated position above the front surface and canbe withdrawn into the component to lower the wafer relative to the frontsurface of the component; the base being configured to move with thesupport member as the support member moves relative to the component;and an adjustable threaded member joined to the base below the componentback surface, the adjustable threaded member moving with the supportmember and physically contacting the component back surface when thesupport member upper surface extends above the component to apredetermined distance, the adjustable threaded member preventing thesupport member upper surface from extending beyond the front surface bymore than the predetermined distance.
 2. The apparatus of claim 1comprising at least three support members.
 3. The apparatus of claim 1wherein the component is a heater and the front surface is a heatedsurface of the heater.
 4. The apparatus of claim 1 wherein theadjustable threaded member is a screw.
 5. The apparatus of claim 1wherein the support member and component are both movable relative toone another.